Recognizing the need for a systematic evaluation of current methods of determining competency to stand trial, including the so-called McGarry instruments developed by the Harvard Laboratory of Community Psychiatry, the Social Science Research Institute, supported by the National Institute of Mental Health, is undertaking a two-year study designed to examine the reliability and validity of various competency assessment methods. The study will examine two cohorts made up of defendants passing through the Boston and Chicago court systems. All defendants will undergo the court-ordered competency assessment procedure normally used in their jurisdiction. In addition, various subpopulations of each cohort will undergo further examinations by teams formed especially for this research project. In each jurisdiction, a cohort of 300 defendants will be selected for intensive study. One hundred defendants will be evaluated by interdisciplinary screening panels trained in accordance with current recommended procedures. The panels will be made up of a mental health professional and a lawyer who are recruited from local professional associations. Eighty defendants will be administered the HLCP Competency Screening Test (a brief incomplete-sentences test), and 120 defendants will be interviewed by either a lawyer or a mental health professional trained in the use of the HLCP Competency Assessment Instrument. A random sample of "competent" and "incompetent" defendants from the CST and CAI conditions will be re-interviewed by an interdisciplinary assessment panel, constituted to parallel the screening panel. Finally, a subset of record for all defendants will be submitted to a blue ribbon panel made up of nationally recognized forensic experts in mental health and law. The study will produce a report comparing the results of the various methods of determining competency with the results obtained by the blue ribbon panel, and evaluating the reliability, in field use, of each method. The goal is to make recommendations as to the most appropriate competency determination procedure for use under normal forensic conditions.